You can submit covers to the Sync catalogue but you must do your best to find and add the original publishing ownership, and make sure to mark the track as a ‘cover’ in the Song Info. The best way to find publishing information is to log into your PRO database and search for the original song where the publishing information will be available.
With regards to Song info, the person who records the cover will own the master rights but the publishing remains with the original publisher. Select the option stating that it’s a cover song. Find the publishing owners info as you have to the best of your knowledge – it’s your responsibility to make sure this is correct. Then create the publishing company/owner as a contact.